Coupling device



April 11, 1944.

F. N. JACOB COUPLING DEVICE v Filed May 16, 1942 Patented Apr. 11, 1944UNITED STATES PATENT OFFICE COUPLING DEVICE poration of IllinoisApplication May 16, 1942, Serial No. 443,321

9 Claims.

The invention pertains to an improved form of coupling device includingcoupled inductors provided with adjustable ferro-magnetic cores forpre-tuning purposes, so that the inductors of the device may beconnected respectively in the circuits to be coupled, after which thecircuits and included inductors may be pre-tuned to any desiredfrequency or frequencies. The coupling device of the invention isadapted for use in radio receivers generally, wherever coupled pro-tunedcircuits are required, together with facilities for accurately adjustingthe inductancs of the coupling device when connected in the circuits ofwhich they are parts,'to accurately tune the circuits to a predeterminedfrequency-or frequencies, to compensate for'inductance and capacitancethat may be included in said circuit respectively. The coupling deviceof the invention is particularl adapted for use as anintermediatefrequency transformer for superheterodyne receivers.

The coupling device of the invention consists essentially of twocoaxially arranged inductors each including an inductance coil and aferromagnetic core adjustable axially relatively to the coil, the coilsbeing preferably arranged in endto-end relation and so spaced from eachother as to secure the desired degree of coupling between said coils.The invention further provides a simple and inexpensive means forindepend ently adjusting the inductance of the inductors from the sameend of the coupling device, thereby avoiding the inconvenience inadjusting the inductors after they are mounted in a radio receiver,incident to adjusting the inductance of one of the inductors from oneend of the'device and adjusting the inductance of the other inrotor fromthe other end of the device, as has frequently been done in the past.

Heretofore, it has been proposed to adjust the vice, provided withpowdered iron cores for adlusting purposes, in a number of ways, forexample, by providing a yoke or framework extending longitudinally ofthe coupling device for adjusting the inductor remote from the outer endof the coupling device which is readily accessible to the workman, whichadjusting devices are relatively expensive to manufacture and tend tointroduce undesired losses in the operation of the coupling device;second, to avoid the need for the connecting yokes-or framework referredto, it has been proposed to avoid the coaxial arrangement and disposethe inductors of the coupling device with their axes in spaced andparallel so coaxially arranged inductors of a coupling derelation, whicharrangement besides resulting in a larger coupling device, alsoincreases its cost of manufacture and introduces the possibilit of zerocoupling occurring, as well as requiring for one of the adjustableinductors a long core stud presenting the possibilities of undesiredoperating effects in connection with the coupling device as a whole.

The difliculties experienced with earlier types of coupling devices ofthe kinds referred to, are entirely overcome by the construction of theinvention, in which the coils of the inductors are mounted coaxially ona single supporting tube in which the cores are disposed for axia1movement relatively to the corresponding inductance coils, the inventionproviding that the coreadjacent the outer or readily available end ofthe coupling device when in use, shall be tubular and be provided with atubular and externally threaded adjusting stud extending through theouter terminal plate of the coupling device, to be readily accessible sothat it may be turned by the workman to adjust the adjacent inductor asdesired; the invention-also provides the core of the inductor remotefrom the outer end of the device, which may be a solid core, with across-slot or equivalent conformation in its end towards the outeradjustable core, as a result of which a correspondingl shaped tool ofsuitable material, may be inserted through the tubular adjusting stud ofthe outer inductor and engage the crossslot in the other core, to adjustthe inductor remote from the outer end of the coupling device asdesired.

,Another object of my invention, using cores of the constructiondescribed, is to so proportion the internal diameter or the tubular coreto its external diameter, that its effective core to coil permeabilityis substantially the same as the effective core to coil permeability ofthe solid core:

The invention will best be understood by reference to the accompanyingdrawing illustrating a preferred embodiment thereof, in which:

Fig. 1 shows the coupling device of the invention in side elevation withthe shield can thereof in vertical, central, sectional view,

Fig. 2 is a plan view of the coupling device shown in Fig. 1 with theshield can removed,

Fig. 3 is a vertical, sectional view through the coupling device to anenlarged scale, taken along the line 8-4 in Fig. 2,

Fig. 4 is a plan view of the coupling device with the shield can inplace thereon,

Fig. 5 is a vertical, sectional view .to an en- 7 largedscale throughthe upper end of the shield can, taken along the line 5-5 in Fig. 4, and

Fig. 6 shows in elevation and to a scale corresponding to that of Fig.3, an adjusting tool adapted to the purpose of adjusting the inductors@own in Fig. 3. i

Similar numerals refer to similar parts throughout the several views.

As shown in Figs. 1 and 2, the coupling device 7 case in pi form,although it will be understood. that the windings of the inductancecoils may, ,have any other form as desired. Also extend-' ingbetween theplates I. and II are four-com ductive bus rods I! (Fig. 2) two ofwhichare shown in Fig. 1 as connected with the terminals of thewindings-of the coil l5, and also connected.

with a tuning capacitor l8. The other two bus rods H. are similarlyconnected with the termi nals of the 'coil i6 and with a tuningcapacitor [9. The inner ends of the bus rods i! are con-' ablesdjustingtool, for example of the had shown in Fig. 6, consisting of a rod M ofinsulating and non-magnetic material, having a diameter slightly smallerthan the bore in the tube 23, and provided at one end with a iiatvextension 21a for engaging the slot 22a in the core 22, said rod 21being provided adjacent its other end with a slender cross-rod 21bhaving projecting ends for entering the cross-slot 22a in the tube 23when it is desired to adiust the core 2!.

As a result of the the coupling device has been connected in desiredcircuits, the coil l6 and its circuit may be pre-tuned to a desiredfrequency by inserting the end 21:! of the adjusting tool through thetube 23 and into engagement with the core 22,. and turning the rod 21until the desired tuning of the circuit including the coil It issecured; similarly, by reversing the rod 21 and a in the sleeve-23 withthe cross-rod 21b,

., the core 2! may be moved axially relatively to the coil I5 until thedesired pre-tuning of the circuit including the said coil 15 iseiIected. It

will be observed that the construction described is simple andinexpensive to manufacture and that it permits .the coupling device tobe of minimum size consistent with any contemplated use, The rods i2 andi3 although preferably metallic, by being connected with diagonallyopposite corners of the plates II and II are subnected 'at the plate H,which is the mounting end of thecoupiing device, with terminal lugs 20for circuit connection purposes. Asmore clearly shown in Fig. 3, tube llcona first ferromagnetic'core 2| for coopera tion with the coil ii and asecond ferromagnetic stantially spaced fromthe coils l5 and II so thattheir eflect on the operation of the inductors is so small as tobenegligible: the same is true of the bus rods H. The invention thusprovides acompact and efiici'ent construction of couplinz core 22 forcooperation with the coil [6. The

core 2| is tubular and has molded into its outer or upper end, the endof an threaded tube 23 having a bore ofsubstantially the same diameteras the bore extending axially through device, and at the same timeprczwide for convenient access for adjustment purposes, to eitherdesired one of the. adjustable cores of the coupling device, throughsame end of the device,

thus avoiding the necessity in using the ecu-- .pling device, ofmakingany tuning adjustments the core 2|. The threads on the tube 23 engageinternal threadsin' a sleeveu'which is shoul dered at its inner end toprovide a centering seatfor the adjacent end or the tube It; said.

sleeve 24' extending centrally through and being rigidly secured to theplate It. As a result of the construction described, turning the tube acorrespondingly moves the core 2! axially in the tube ii to change-theinductance of the coil Ii for the purpose of tuning the circuit in whichthe coil l5 may be included.

The core 22 is provided with a threaded stud 25 extending axiallytherefrom through the plate Ii, which is in threaded'engagement with anut 25 secured to said plate, said nut being of any well knownconstruction yieldingly engaging the threads on the stud 25 to preventaccidental turning of said stud. Said nut 28 is preferably provided witha tubular extension through the plate ii securing a disc its in centeredrelation on. the plate ii to form a centering seat. for the adjacent endor the tube id. The end of the stud 2d outside or the nut is providedwith a slot 25a to facilitate initially assembling the stud 'in the nutit before the coupling device is connected for use, and said core isprovided at s Outer pper end with a cross-slot 22a for accuratelyadjusting the core 22 to tune the circuit in which the coil in may beconnected, by correspondingly moving the core 22 axially the'tube i6. 7

from the end of coupling device employed y to mount the device on asupport or chassis. "As illustrated 1 and 4, the coupling device mayconveniently be contained in a shield can 28 held in place'around theplates II and ii by nuts 29 engaging threaded extensions of the rods l2and 83. The outer end of the shield can. is provided with an aperture 30of substantially theexternal diameter of the tube 23,

and a shutter 8! is pivotally mounted on the inner surface of the end ofthe can 28, by a rivet 32 so that said shutter may be moved by a lugtietoclose or open the aperture 3! as desired. The shutterdi ispreferably provided with an onset portion Mb entering the aperture lidfor the closed position of the shutter, to-hold the shutter in itsclosed position unless it is desired .to open the aperture at which timethe opening movement is permitted by the yieldhis nature of the materialoi the shutter 3|. As shown in Fig. 2 a spring t3 engages at itsmidportion, the external suriace oi thetube 23, and esmnds at its endsinto engagement with the extensions of the rods 52 and it, to hold thetube 28 and core 23 in any adjustment that may be given them.

for ens s ns a suit 35;

With the cores 2i and 22 constructed as described, and each having anexternal diameter or and with the tubular core 2i having an internaldiameter of .2", I find that the core to coil permeability of the core25 is substantially the cane as the core to, coil permeability of thecore.

construction described, when a While I have shown my invention in theparticular embodiment described, I do not limit myself thereto as I mayemploy equivalents thereof without departing from the scope of theappended claims.

Having thus described my invention, what I claim-is:

1. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted for axial movement in said tube and having a firstscrewthreaded holding connection, and a second ferromagnetic coremounted in said tube for axial movement and spaced axially from saidfirst core and having a rod-engaging conformation accessible to anadjusting rod extended through said aperture in said first core andhaving a second screw-threaded holding connection, whereby said secondcore may be turned and adjusted.

2. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted for axial move ment in said tube and having a firstscrewthreaded holding connection, a second ferromagnetic core mounted insaid tube for axial movement and spaced axially from said first core andhaving a rod-engaging conformation accessible to an adjusting rodextended through said aperture in said first core and having a secondscrew-threaded holding connection, whereby said second core may beturned and adjusted, and means independently restraining said coresagainst accidental turning.

3. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted for axial movement in said tube and having a firstscrewthreaded holding connection, a second ferromagnetic core mounted insaid tube for axial movement and spaced axially from said first core andhaving a rod-engaging conformation accessible to an adjusting rodextended through said aperture in said first core and having. a secondscrew-threaded holding connection, whereby said 'second core may beturned and adjusted, a shield can containing said tube and said coresand having an end wall adjacent said first holding connection andapertured in line therewith, and a shutter pivotally connected with saidend wall for closing said can aperture.

4. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted for axial move ment in said tube and having a firstscrewthreaded holding connection, and a second ferromagnetic coremounted in said tube for axial movement and spaced axially from saidfirst core and having a rod-engaging conformation accessible to anadjusting rod extended through said aperture in said first core andhaving a second screw-threaded holding connection, whereby said secondcore may be turned and adjusted, said first screw-threaded holdingconnectlon including an externally threaded sleeve extending axiallyfrom said first core and having a bore for loosely receiving saidadjusting rod.

5. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic 6 fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted for axial movement in said tube. and having a firstscrewthreaded holding connection, and a second ferromagnetic coremounted in said tube for axial movement and spaced axially from saidfirst core and having a rod-engaging conformation accessible to anadjusting rod extended through said aperture in said first core andhaving a second screw-threaded holding connection, whereby said secondcore may be turned and adjusted, said cores having substantially thesame external diameters as each other.

6. An adjustable ferromagnetic core assembly 20 for use with highfrequency alternating magnetic fields including in combination a tube ofinsulating material, a firstferromagnetic core having an axial apertureand mounted for axial move ment in said tube and having a first screw-25 threaded holding connection, and a second fermmagnetlc core mountedin said tube for axial movement and spaced axially from said first coreand having a rod-engaging conformation accessible to an adjusting rodextended through 3 said aperture in said first core and having a secondscrew-threaded holding connection, whereby said second core may beturned and adjusted, said first core having an internal diameter notsubstantially in excess of half of its 35 external diameter.

7. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted for anal movement in said tube and having a firstscrewthreaded holding connection, and a second ferromagnetic coremounted in said tube for axial movement and spaced axially from saidfirst core and having a rod-engaging conformation accessible to anadjusting rod extended through said aperture in said first core andhaving a second screw-threaded ,holding connection, whereby said secondcore may be turned and adjusted, said cores having substantially thesame external diameters as each other, and said first core having aninternal diameter not sill stantially in excess of half of its externaldiameter.

8.4m adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic fields including in combination a tube ofinsulating material, a first ferromagnetic core having an axial apertureand mounted ior axial movement in said tube and having a firstscrewthreadecl holding connection, and a second ferromagnetic coremounted in said tube for axial movement and spaced axially from saidfirst core and having a rod-engaging conformation accessible to anadjusting rod extended through said aperture in said first 'core andhaving a second screw-threaded holding connection, whereby said secondcore may be turned and adjusted, said cores having substantially thesame high-frequency permeability.

9. An adjustable ferromagnetic core assembly for use with high frequencyalternating magnetic 4 messes s an si aperture and mounted for asdaimovemeat in said tube and having s fisst screwi ii'eeclezi holdingconnection, and a second imaetic core mounted in said tme for axialvement and spaced axially from said first core and having atori-engaging conformation accessible to an adjusting rod extendedthrough said wee in said first sore and having a second screw-threaded!holding connection whereby said second core may be turned and adjusted,said cores having substantially the same external diameters as eechother, and said first core ha aninternal diameter not substsntiaily inexcess of half of its external diameter, said cores having substantiallythe same high-frequency permeability.

1- N. JACOB.

